Gunzip: added missing ngx_http_clear_etag().

src/http/modules/ngx_http_gunzip_filter_module.c

@@ -165,6 +165,7 @@ ngx_http_gunzip_header_filter(ngx_http_request_t *r)
 
     ngx_http_clear_content_length(r);
     ngx_http_clear_accept_ranges(r);
+    ngx_http_clear_etag(r);
 
     return ngx_http_next_header_filter(r);
 }